Human cartilage neoplasms present problems in management related to (a) difficulties in determining whether a particular tumor is benign or malignant based on histologic appearance; (b) difficulties in assessing degrees of malignancy in chondrosarcomas. Because of the difficulty in arriving at a correct diagnosis, patients with chondrosarcoma continue to be treated initially by currettage or local excision with a high incidence of local recurrence. The long term objective of the proposed research is to develop a biochemical method to reveal preoperatively in a patient the presence of a chondrosarcoma; to demonstrate unequivocally that the neoplasm is a malignant rather than a benign cartilage neoplasm; to assess the degree of malignancy of the chondrosarcoma; and to determine postoperatively following surgical removal whether the patient remains free of recurrence or develops local recurrence or metastasis. We have recently identified a protein species present in significant amounts in benign and malignant cartilage neoplasms. This protein species appears to be a major component of the extracellular matrix of cartilage tumors. The specific aims of the proposed studies are: To develop methods for the isolation of this protein species to homogeneity, and to chemically and physically characterize this protein; to show that the protein is synthesized by chondrocytes and secreted into the extracellular matrix; to develop a radioimmunoassay which can be used to demonstrate the presence of the protein species in the serum of patients with benign and malignant cartilage tumors, and to measure its serum levels; to determine whether there is a relation between the serum level of the protein species and the type of cartilage neoplasm (benign or malignant), the histologic grade of the chondrosarcoma, its degree of malignancy, and/or its size.